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Biomedical subjects

B Lind

Publications and source records attributed to B Lind.

At least 19 recordsLinked to original sources
PubMed2005

Uptake of radionuclides by vegetation at a High Arctic location.

Radionuclide levels in vegetation from a High Arctic location were studied and compared to in situ soil concentrations. Levels of the anthropogenic radionuclide 137Cs and the natural radionuclides 40K, 238U, 226Ra and 232Th are discussed and transfer factor (TF) values and aggregated transfer (Tag) values are calculated for vascular plants. Levels of 137Cs in vegetation generally followed the order mosses > lichen > vascular plants. The uptake of 137Cs in vascular plants showed an inverse relationship with the uptake of 40K, with 137Cs TF and Tag values generally higher than 40K TF and Tag values. 40K activity concentrations in all vegetation showed little correlation to associated soil concentrations, while the uptake of 238U, 226Ra and 232Th by vascular and non-vascular plants was generally low.

Air Pollutants, Radioactive↗
PubMed2004

Cellular parameters for track structure modeling of radiation hazard in space.

Based on irradiation with 45 MeV/u N and B ions and with Co-60 gamma rays, cellular parameters of Katz's track structure model have been fitted for the survival of V79-379A Chinese hamster lung fibroblasts. Cellular parameters representing neoplastic transformations in C3H10T/1/2 cells after their irradiation with heavy ion beams, taken from earlier work, were also used to model the radiation hazard in deep space, following the system for evaluating, summing and reporting occupational exposures proposed in 1967 by a subcommittee of NCRP. We have performed model calculations of the number of transformations in surviving cells, after a given fluence of heavy charged particles of initial energy 500 MeV/u, penetrating thick layers of cells. We take the product of cell transformation and survival probabilities, calculated along the path lengths of charged particles using cellular survival and transformation parameters, to represent a quantity proportional to the "radiation risk factor" discussed in the NCRP document. The "synergistic" effect of simultaneous charged particle transfers is accounted for by the "track overlap" mode inherent in the model of Katz.

Animals↗
PubMed2004

Left ventricular isovolumic velocity and duration variables calculated from colour-coded myocardial velocity images in normal individuals.

AIMS: To describe the normal myocardial velocity profile during the isovolumic contraction and relaxation period at four different locations within left ventricular base and to establish normal age and gender related isovolumic time and velocity values. METHODS AND RESULTS: In 49 healthy individuals (26 women/23 men) in age groups 21-49 and 50-76 years, tissue velocity profiles and 2D-data were acquired at high temporal resolution (90-147 frames/s) for a subsequent off-line analysis using software enabling retrieval of myocardial Doppler velocity and 2D/anatomical M-mode information from different cardiac locations during the same cardiac cycle. The obtained velocity curves during the isovolumic contraction and relaxation period were usually biphasic and displayed clear regional differences in their respective positive and negative maximal velocities. Besides some gender related differences, mainly in the duration of the positive and negative velocity wave components during the isovolumic contraction period, a clear age-dependent increase in the duration of the isovolumic relaxation phase and its negative and positive velocity components was observed. CONCLUSION: Modern tissue Doppler imaging supplemented by anatomical M-mode images of the mitral and aortic valve movements allows a proper analysis of the rapid isovolumic myocardial movements. The presented normal isovolumic time and velocity values may prove useful for studies of myocardial function.

Adult↗
PubMed2004

Assessment of the radiological impacts of historical coal mining operations on the environment of Ny-Alesund, Svalbard.

Mineral extraction activities, such as those conducted by oil, gas and coal industries, are widespread throughout the Arctic region. Waste products of these activities can result in significant contributions to the radioactive burden of the surrounding environment due to increased concentrations of naturally occurring radioactive materials (NORM) to levels that would not normally be found in the environment. Coal mining operations commenced in the early 1900s on Svalbard and have been conducted at a variety of locations on the archipelago since then. Coal contains radionuclides of the uranium and thorium series as well as 40K. Extraction and processing of coal can result in releases of these radionuclides to the broader environment with subsequent impact on the human and non-human inhabitants of the area. This paper presents the results of a study on environmental radioactivity resulting from historical coal mining operations conducted at Ny-Alesund, Spitsbergen, in the Svalbard archipelago. Activity concentrations of radionuclides found in materials associated with these operations are presented as well as the results of a spatial dosimetric survey conducted over an area affected by coal mining.

Arctic Regions↗
PubMed2004

Biologically effective doses in radiotherapy of cervical carcinoma*.

Presented study evaluates biologically effective dose (BED) in patients receiving low-medium dose-rate (LDR/MDR) brachytherapy (BRT) plus external beam radiotherapy (XRT) based on tumor cell proliferation values in cancer of the cervix patients. This study includes 229 patients treated entirely by radiotherapy at the Centre Oncology in Krakow. Doses to Point A were estimated for total treatment for each brachytherapy insertion. BED3 were calculated for reference points in the rectum. The linear quadratic equation was used to calculate BED, which is proportional to log cell kill, and the normalized total dose (NTD), that is, equivalent to a 2 Gy fraction schedule. In BEDs 10 calculation overall treatment time for each patient. Tumor proliferation rate was based on Bromodeoxyuridine labeling index (BrdUrdLI) assessed on biopsy material before beginning the radiotherapy. Total BED at those points was summed for each patient. The medium overall treatment time was 90 days (range 30--210). The mean calculated total BED for point A for tumour and "early reactions" was equal to 104.0 Gy10 and 229.0 Gy3 for the rectum, equivalent to NTD=86.6 Gy and 137.4 Gy in 2 Gy fractions, respectively. Kaplan-Meier analysis revealed that age >50 years, higher than mean BRBEDs and totBEDs doses, gaps in treatments shorter than 40 days and disease free survival (DFS) was significant prognostic factor for overall survival. In the multivariate Cox anaysis age >50 years, BRBED10 >77 Gy and gaps ?40 days appeared to be significant for overall survival. None of the examined parameters was significant for tumor control. However, patientś age and shorter gaps in the treatment were predictive for DFS.

Carcinoma↗
PubMed2003

Gamma-emitting natural and anthropogenic radionuclides in the terrestrial environment of Kongsfjord, Svalbard.

This paper presents results obtained from a radiometric survey, conducted by the Norwegian Radiation Protection Authority, into the levels of gamma-emitting radionuclides, both anthropogenic and natural, in the terrestrial environment of Kongsfjorden, which lies on the North-Western Coast of Spitsbergen in the Arctic archipelago of Svalbard (79 degrees N, 12 degrees E). Samples of terrestrial matrices were taken during field campaigns conducted between 2000 and 2002 and analysed for a range of gamma-emitting radionuclides. The objectives of this study included an assessment of the levels of gamma-emitting radionuclides in the terrestrial environment of the region, identification of processes and activities that influence the accumulation and redistribution of such nuclides within the region and elucidation of the behaviour of such radionuclides within a high arctic environment. Results indicate a quite homogenous spatial distribution of such radionuclides within the study area and highlight the relatively low levels of contamination by the anthropogenic radionuclide, 137Cs, on Svalbard. Average values and ranges of the radionuclides activities in surface soils (0-3 cm) were: 238U 42 Bq/kg (17-134), 226Ra 43 Bq/kg (12-137), 232Th 21 Bq/kg (4-52), 40K 283 Bq/kg (31-564), 137Cs 35 Bq/kg (1-146). Average levels of these nuclides in avian faecal materials were 238U 63 Bq/kg, 226Ra 54 Bq/kg, 232Th 19 Bq/kg, 40K 365 Bq/kg, 137Cs 78 Bq/kg. Enrichment of radionuclides is apparent in soils taken from locations close to bird colonies in the locale, maximum levels of the radionuclides being found in samples associated with such colonies. The results indicate that this is due to concentration of such radionuclides within the faecal material of the birds and subsequent enrichment of the nearby soils either via direct incorporation of the faeces into the soil or by leaching processes. The results indicate that this process may result in contamination of non-related species, such as Svalbard reindeer (Rangifer tarandus playrhynchus), via pathways other than the traditionally accepted route of atmospheric deposition-vegetation-reindeer.

Animals↗
PubMed2003

Feasibility and reproducibility of off-line tissue Doppler measurement of regional myocardial function during dobutamine stress echocardiography.

AIMS: Off-line post-processing of colour tissue Doppler from digital loops may allow objective quantification of dobutamine stress echocardiography. We assessed the reproducibility of off-line measurements of regional myocardial velocities. METHODS AND RESULTS: Nine observers analysed 10 studies, each making 2400 observations. Coefficients of variation in basal segments from apical windows, at rest and maximal stress, were 9-14% and 11-18% for peak systolic velocity, 16-18% and 17-19% for time-to-peak systolic velocity, 9-17% and 18-24% for systolic velocity time integral, and 18-23% and 21-27% for systolic acceleration. Coefficients of variation for diastolic velocities in basal segments at rest were 11-40%. Coefficients of variation for peak systolic velocity were 10-24% at rest and 14-28% at peak in mid segments, and 19-53% and 29-69% in apical segments. From parasternal windows coefficients of variation for peak systolic velocity were 14-16% in basal posterior, and 19-29% in mid-anterior segments. High variability makes measurement unreliable in apical and basal anterior septal segments. The feasibility of obtaining traces was tested in 92 subjects, and >90% in all basal and mid segments apart from the anterior septum. CONCLUSION: Quantification of myocardial functional reserve by off-line analysis of colour tissue Doppler acquired during dobutamine stress is feasible and reproducible in 11 segments of the left ventricle. The most reliable measurements are systolic velocities of longitudinal motion in basal segments.

Blood Flow Velocity↗
PubMed2002

The accidental sinking of the nuclear submarine, the Kursk: monitoring of radioactivity and the preliminary assessment of the potential impact of radioactive releases.

Measurements of samples taken from the close vicinity of the Kursk during two expeditions to the site in August and October 2000, indicate that no leakage of radionuclides from the reactors has been observed. Only background levels in the range 0.0-0.1 microSv/h have been measured by use of the remote operating vehicle (ROV) or by the divers working on and inside the submarine. Preliminary model calculations based on two different scenarios, representing short- and long-term releases of 100% of the reactors radionuclide inventory, show that the impact on man and the environment from the Kursk should not be deemed very serious. The conservative estimates indicate a maximum 137Cs activity concentration in fish in the order of about 80-100 Bq/kg and a total collective dose of 97 manSv.

Accidents↗
PubMed2002

Temporal trends for 99Tc in Norwegian coastal environments and spatial distribution in the Barents Sea.

The objective of this study was to reassess 99Tc transit times and transfer factors, from Sellafield to northern Norway, and to determine the extent of 99Tc migration to the Barents Sea. Filtered seawater samples were collected on a monthly basis from Hillesøy, northern Norway, and in February 1999 from the Barents Sea. Results showed an increase in levels of 99Tc at Hillesøy where activity concentrations have increased from a baseline of 0.2-0.4Bq m(-3) to a maximum of 1.6 Bq m(-3). A transit time of 42 months and a transfer factor of 6Bq m(-3) per PBq a(-1) have been derived, using cross-correlation analysis. The current study predicts that future levels are unlikely to increase dramatically over the levels observed in 1998. Levels of 99Tc in the Barents Sea ranged from 0.2 Bq m(-3) to 1.1 Bq m(-3) showing the influence of new 99Tc inputs by early 1999.

Environmental Pollutants↗
PubMed2002

Radioactive contamination in the marine environment adjacent to the outfall of the radioactive waste treatment plant at ATOMFLOT, northern Russia.

RTP "ATOMFLOT" is a civilian nuclear icebreaker base located on the Kola Bay of northwest Russia. The objectives of this study were to determine the distributions of man-made radionuclides in the marine environment adjacent to the base, to explain the form of the distributions in sediments and to derive information concerning the fate of radionuclides discharged from ATOMFLOT. Mean activity concentrations (d.w.) for surface sediment, of 63 Bq kg(-1 137Cs, 5.8 Bq kg(-1) 90Sr and 0.45 Bq kg(-1 239,240)Pu were measured. Filtered seawater activity levels were in the range of 3--6.9 Bq m(-3) 137Cs, 2.0-11.2 Bq m(-3) 90Sr, and 16-40 m Bq m(-3), 239,240Pu. Short-lived radionuclides were present at sediment depths in excess of 10cm indicating a high degree of sediment mixing. Correlations of radionuclide activity concentrations with grain-size appear to be absent; instead, the presence of relatively contaminated sediment appears to be related to the existence of radioactive particles.

Environmental Monitoring↗
PubMed2002

Analysis of temporal requirements for myocardial tissue velocity imaging.

AIMS: Movements of myocardial walls include components of high velocity and short duration calling for a high sampling rate in the acquisition of tissue velocity imaging data. This study aims at establishing the optimal sampling requirements for tissue velocity imaging measurements. METHODS AND RESULTS: In 16 healthy individuals, tissue velocity imaging data were acquired at a frame rate of 141-203 frames/s for a subsequent off-line analysis using software enabling a reduction of the sampling rate to 50%, 25% and 12.5% of the initial frame rate. Different components of the myocardial velocity profile were measured at each of these frame rates. The deviation of the results from the initial values increased markedly at decreasing frame rates, producing an underestimation of peak systolic and diastolic velocities, most other measured parameters being overestimated. A cut-off point for an acceptable < or =10% deviation of the results corresponded to at least 70 frames/s for peak systolic and early diastolic velocity, and to at least 100 frames/s for other systolic and diastolic parameters. CONCLUSION: A high sampling rate is essential for a proper rendering of tissue velocity imaging signals, too low frame rates resulting in inferior accuracy of the results. This should be kept in mind while viewing reported tissue velocity imaging data.

Adolescent↗
PubMed2001

Saccharomyces cerevisiae leukotriene A4 hydrolase: formation of leukotriene B4 and identification of catalytic residues.

Leukotriene A(4) hydrolase in mammals is a bifunctional zinc metalloenzyme that catalyzes the hydrolysis of leukotriene A(4) into the proinflammatory mediator leukotriene B(4), and also possesses an aminopeptidase activity. Recently we cloned and characterized an leukotriene A(4) hydrolase from Saccharomyces cerevisiae as a leucyl aminopeptidase with an epoxide hydrolase activity. Here we show that S. cerevisiae leukotriene A(4) hydrolase is a metalloenzyme containing one zinc atom complexed to His-340, His-344, and Glu-363. Mutagenetic analysis indicates that the aminopeptidase activity follows a general base mechanism with Glu-341 and Tyr-429 as the base and proton donor, respectively. Furthermore, the yeast enzyme hydrolyzes leukotriene A(4) into three compounds, viz., 5S,6S-dihydroxy-7,9-trans-11,14-cis-eicosatetraenoic acid, leukotriene B(4), and Delta(6)-trans-Delta(8)-cis-leukotriene B(4), with a relative formation of 1:0.2:0.1. In addition, exposure of S. cerevisiae leukotriene A(4) hydrolase to leukotriene A(4) selectively inactivates the epoxide hydrolase activity with a simultaneous stimulation of the aminopeptidase activity. Moreover, kinetic analyses of wild-type and mutated S. cerevisiae leukotriene A(4) hydrolase suggest that leukotriene A(4) binds in one catalytic mode and one tight-binding, regulatory mode. Exchange of a Phe-424 in S. cerevisiae leukotriene A(4) hydrolase for a Tyr, the corresponding residue in human leukotriene A(4) hydrolase, results in a protein that converts leukotriene A(4) into leukotriene B(4) with an improved efficiency and specificity. Hence, by a single point mutation, we could make the active site better suited to bind and turn over the substrate leukotriene A(4), thus mimicking a distinct step in the molecular evolution of S. cerevisiae leukotriene A(4) hydrolase toward its mammalian counterparts.

Amino Acid Sequence↗
PubMed2001

Involvement in caregiving and adjustment to death of a spouse: findings from the caregiver health effects study.

CONTEXT: Most deaths in the United States occur among older persons who have 1 or more disabling conditions. As a result, many deaths are preceded by an extended period during which family members provide care to their disabled relative. OBJECTIVE: To better understand the effect of bereavement on family caregivers by examining predeath vs postdeath changes in self-reported and objective health outcomes among elderly persons providing varying levels of care prior to their spouse's death. DESIGN AND SETTING: Prospective, population-based cohort study conducted in 4 US communities between 1993 and 1998. PARTICIPANTS: One hundred twenty-nine individuals aged 66 to 96 years whose spouse died during an average 4-year follow-up. Individuals were classified as noncaregivers (n = 40), caregivers who reported no strain (n = 37), or strained caregivers (n = 52). MAIN OUTCOME MEASURES: Changes in depression symptoms (assessed by the 10-item Center for Epidemiological Studies-Depression [CES-D] scale), antidepressant medication use, 6 health risk behaviors, and weight among the 3 groups of participants. RESULTS: Controlling for age, sex, race, education, prevalent cardiovascular disease at baseline, and interval between predeath and postdeath assessments, CES-D scores remained high but did not change among strained caregivers (9.44 vs 9.19; P =.76), while these scores increased for both noncaregivers (4.74 vs 8.25; F(1,116) = 14.33; P<.001) and nonstrained caregivers (4.94 vs 7.13; F(1,116) = 4.35; P =.04). Noncaregivers were significantly more likely to be using nontricyclic antidepressant medications following the death than the nonstrained caregiver group (odds ratio [OR], 12.85; 95% confidence interval [CI], 1.02-162.13; P =.05). The strained caregiver group experienced significant improvement in health risk behaviors following the death of their spouse (1.47 vs 0.66 behaviors; F(1,118) = 20.23; P<.001), while the noncaregiver and nonstrained caregiver groups showed little change (0.27 vs 0.27 [P =.99] and 0.46 vs 0.27 [P =.39] behaviors, respectively). Noncaregivers experienced significant weight loss following the death (149.1 vs 145.3 lb [67.1 vs 65.4 kg]; F(1,101) = 8.12; P =.005), while the strained and nonstrained caregiving groups did not show significant weight change (156.2 vs 155.2 lb [70.3 vs 69.8 kg] [P =.41] and 156.2 vs 154.0 lb [70.3 vs 69.3 kg] [P =.12], respectively). CONCLUSIONS: These data indicate that the impact of losing one's spouse among older persons varies as a function of the caregiving experiences that precede the death. Among individuals who are already strained prior to the death of their spouse, the death itself does not increase their level of distress. Instead, they show reductions in health risk behaviors. Among noncaregivers, losing one's spouse results in increased depression and weight loss.

Aged↗
PubMed2001

[CSF-analyses in clinical diagnosis of Creutzfeldt-Jakob disease. A literature review and three cases from routine clinical practice].

The clinical diagnosis of Creutzfeldt-Jakob disease (CJD) is often difficult, since the clinical presentation varies between patients and is often uncharacteristic. Therefore, CJD is often not suspected until late in the disease process, due to the rapid progress of the disease. Suspected CJD is, however, frequent in routine clinical practice, in the investigation of patients with rapidly progressing dementia and/or uncharacteristic neurological symptoms. We present results from cerebrospinal fluid (CSF) analyses in CJD, focusing on the two neuron-specific proteins 14-3-3 and tau. Analysis of 14-3-3 protein is performed by Western blotting, in which 14-3-3 is either detectable in CSF or not, while CSF-tau is analyzed using quantitative ELISA methodology, in which a markedly increased CSF level of tau (< 1500 pg/mL) is indicative of CJD. Tau and 14-3-3 findings show comparable sensitivity and specificity, higher than the presence of spike and wave complexes on an EEG. The increase in CSF-tau in CJD is substantially higher than in Alzheimer's disease, with low overlap between the disorders. Instead, false positive results are found in disorders with massive acute neuronal damage (encephalitis, stroke and CNS tumors). In cases in which these disorders cannot be differentiated from CJD on clinical grounds, they can often be identified by MRT or by the finding of blood-brain barrier damage or signs of inflammation upon CSF analysis. CSF-tau is increasingly used in the routine diagnosis of Alzheimer's disease, and the analysis also seems to be of use in the clinical diagnosis of CJD. We also present three cases from routine clinical practice, all with a marked increase in CSF-tau, which was the only positive objective sign in two of the cases.

Aged↗
PubMed2001

Deterioration in peak systolic velocity is closely related to ischaemia during angioplasty: a vectorcardiographic and tissue Doppler imaging study.

We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.

Aged↗
PubMed2001

Street-level drug law enforcement and entry into methadone maintenance treatment.

AIMS: To test the hypothesis that drug law enforcement encourages entry into methadone maintenance treatment. DESIGN: Survey conducted as face-to-face interviews in methadone clinics, at needle exchange centres and on the street, in areas of widespread heroin dealing and use. SETTING: Sydney, Australia. PARTICIPANTS: Heroin users. MEASUREMENTS: Self-reported data on personal characteristics, and experience of drug law enforcement and methadone maintenance treatment. FINDINGS: Although keeping their relationship/family together emerged as the most important reason given by respondents for entering treatment, avoiding more trouble with police/courts was also rated by the majority of respondents as an important or very important reason for entering treatment. The results of logistic regression analysis show that, after controlling for other factors, heroin users who have had a friend or family member imprisoned are more likely to have tried methadone maintenance treatment. A heroin user's own experience of arrest and imprisonment was also found to increase the likelihood of having tried treatment but only when age and length of time as a regular user (which were related to the user's experience of arrest and imprisonment) were excluded from the set of control variables. Despite having extensive histories of contact with the police and criminal justice system, however, Asian, Middle Eastern and Aboriginal respondents showed less proclivity to enter treatment than Caucasian respondents. CONCLUSION: Drug law enforcement may have a role to play in heroin demand reduction but its effects are not evident for all ethnic groups and the separate effects of contact with police, age and time spent in the heroin market remain unclear.

Adolescent↗
PubMed2001

Symptomatic type 1 protein C deficiency caused by a de novo Ser270Leu mutation in the catalytic domain.

Heterozygosity for a C8524T transition in the protein C gene converting Ser270(TCG) to Leu(TTG) in the protease domain was identified in a family with venous thrombosis. The mutation was associated with parallel reduction in plasma levels of protein C anticoagulant activity and protein C antigen, which is consistent with a type 1 deficiency. Transient expression of mutant protein C cDNA in human kidney 293 cells and analysis of protein C antigen in culture media and cell lysates showed that the secretion of mutant protein compared with wild-type protein was reduced by at least 97% while the intracellular content of mutant and wild-type protein was similar. Northern blot analysis of total mRNA from transfected cells showed no reduction of the mutant protein C mRNA compared with wild-type protein C mRNA. Collectively, these results indicate that the Ser270Leu mutation in the affected family caused the plasma protein C deficiency and are consistent with a disease mechanism that involves synthesis of mutant protein followed by intracellular degradation before its secretion into the extracellular space. The mutation was not present in the parents of the proband, suggesting a de novo mutation. Non-paternity was excluded after the analysis of three intragenic protein C polymorphisms and six dinucleotide repeat allele sets located in five different chromosomes.

Adult↗